A good enough idea: hardbound reprints, loosely grouped by theme, of some classic science-fiction stories whose awkward length makes them difficult to come by in conventional anthologies. But Anderson's ""Gypsy""--a rather flaccid story of spaceman's wanderlust returning to the peaceful Earthlike colony of Harbour--is certainly too short to warrant Bova's remarks about salvaging works of ""difficult lengths."" On the other hand, it is always a pleasure to renew acquaintance with Eric Frank Russell's often (and justly) anthologized ""And Then There Were None."" The wisecracking prose now has a faintly antique ring, but the story--about a shipload of Terran bigwigs encountering a planetful of ""Gands"" dedicated to the principles of civil disobedience--looks better every time round. And Asimov's ""Profession,"" set in a society where specialized instant programming of workers has replaced all other education, is almost an object lesson in maintaining the intellectual suspense of a science-fiction hypothesis.